臺灣博碩士論文加值系統

在一維的線性陣列束波器中，會產生一圓錐形的混淆曲面，這將使得束波器對這圓錐面方向上所入射之信號造成混淆。因此在本論文中，除了使用一維的均勻線性陣列設計束波器外，更將接收陣列拓展至二維的矩形陣列，以克服一維線性陣列對入射信號所造成之混淆。
在以聚焦結構處理寬頻信號之演算法中，大多都需要先進行方位預估的步驟，如此便造成對預估方位之敏感。於本論文中將參考[1]，設計一使用信號子空間聚焦法之寬頻束波器，利用此法便可省去方位預估之步驟。
最後我們將利用行向量聚焦法來設計寬頻之束波器，此法以簡易信號子空間估測法來取代信號子空間聚焦法因估測每一頻率的信號子空間所需之特徵分解，故可降低計算量。

1-D uniform linear array (ULA) beamformer would cause a conical ambiguity surface, and the beamformer would be aliased by the propagating signals coming from this conical surface. Therefore in this thesis, we are not only using 1-D ULA to design the beamformer but also using the 2-D rectangular array to overcome the problem.
For wideband signal processing, most focussing algorithms require preliminary estimate of the source angle resulting in the estimation bias. In this thesis, we adopt signal subspace focussing (SSF) method to design a wideband beamformer to omit preliminary estimate of the source angle.
Finally, we adopt the column vector focusing method to design the wideband beamformer. Using this method, we can avoid the eigenvalue decomposition when estimate the signal subspace in SSF is estimated, therefore reducing the computational complexity.

第一章 緒論 1
1.1. 前言 1
1.2. 研究動機 2
1.3. 論文架構介紹 3
第二章 束波器的基本觀念 5
2.1 前言 5
2.2. 束波器的簡介 5
2.3. 方位定義 7
2.4. 束波之權重 8
2.5 波束圖 10
2.6. 窄頻與寬頻 11
第三章 窄頻束波器之設計 14
3.1. 延遲和束波器 14
3.1.1. 原理介紹 15
3.1.2. 二維矩形陣列延遲和束波器 17
3.1.3. Dolph-Chebyshev Taper之應用 20
3.2. 最小變異無失真響應(MVDR)束波器 23
3.2.1. 原理介紹 23
3.2.2. 二維矩形陣列MVDR束波器 27
3.2.3. Dolph-Chebyshev Taper之應用 28
3.3. 模擬結果 30
3.3.1. 電腦模擬(一) 30
3.3.2. 電腦模擬(二) 35
第四章 寬頻束波器之設計 40
4.1. 前言 40
4.2 寬頻信號模型 42
4.3. 以訊號子空間聚焦法為基礎之寬頻MVDR束波器45
4.4. 以行向量聚焦法為基礎之寬頻MVDR束波器 50
4.5. 模擬結果 56
第五章 結論與未來展望 62
參考文獻 64

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